At a Wells Fargo conference today, AT&T’s president of technology operations said running virtual network functions (VNFs) in live networks was “not for the faint of heart.”

“When you’ve got functions like border gateway controller or firewall, and you’ve got it running on virtualized machines and different data centers, the control and management of that is not for the faint of heart,” said AT&T’s president of technology operations, Bill Smith, per a Seeking Alpha transcript. “But it’s an exciting new step for us and we’re making very good progress.”

AT&T is stretching toward its ultimate goal to have 75 percent of its network virtualized by 2020. For 2016, its benchmark is to have 30 percent of its network functions virtualized by the end of the year.

“We’ve got something on the order of 15 million wireless customers running on a virtualized core on a network today,” said Smith.

AT&T is making a big push into Mexico and Latin America. Smith says its work with software defined networking (SDN) and network functions virtualization (NFV) is helping the company expand globally.

“I won’t say [it’s] easy, but it enables us to basically drop nodes in anywhere around the world," he said. "Since this is basically a software-based service capability, we can provide seamless functionality and identical capability anywhere in the world as long as we’ve got the right connectivity.”

AT&T has previously said by the end of 2016 it expects to have 105 data centers in its integrated cloud, which serves as the basis for its virtualization strategy.

Smith also said today AT&T is starting to see some benefits from its Domain 2.0 strategy to add more vendors to its supplier list to drive SDN and NFV and lower its costs.

“This is more exciting to me than any change that I’ve seen in my career, whether it was wireline to wireless, copper to fiber, circuit to packet,” he said. “You name it, because this is fundamentally changing us from a hardware-oriented company to a software company.”